docs: def set_dtreat_interp_indt(self, indt=None):
          """ Set the indices of the times for which to interpolate data
  
          The index can be provided as:
              - A 1d np.ndarray of boolean or int indices
                  => interpolate data at these times for all channels
              - A dict with:
                  * keys = int indices of channels
                  * values = array of int indices of times at which to interpolate
  
          Time indices refer to self.ddataRef['t']
          Channel indices refer to self.ddataRef['X']
          """
          lC = [indt is None, type(indt) in [np.ndarray,list], type(indt) is dict]
          assert any(lC)
          if lC[2]:
              lc = [type(k) is int and k<self._ddataRef['nch'] for k in indt.keys()]
              assert all(lc)
              for k in indt.keys():
                  assert hasattr(indt[k],'__iter__')
                  indt[k] = _format_ind(indt[k], n=self._ddataRef['nt'])
          elif lC[1]:
              indt = np.asarray(indt)
              assert indt.ndim==1
              indt = _format_ind(indt, n=self._ddataRef['nt'])
          self._dtreat['interp-indt'] = indt
          self._ddata['uptodate'] = False